An optimized method for determining beta-emitting in the presence of alpha-emitting nuclides was developed using a liquid scintillation counting system. Pulse shape analysis (PSA) level was set using pulse-shape discrimination method and the counting channel was adjusted for maximum value of figure of merit using the 241pu standard source. The volume of scintillant was determined for the maximum value of counting efficiency. This optimized method has been applied to environmental samples to measure concentration of in soils and mosses. Also it has been identified the origin of Pu deposited in Korea from the activity ratio of .

After high-dose irradiation(8 Gy). the viability of lymphocyte with a prior low-dose irradiation was 3.7-fold higher than that without a prior low-dose irradiation The viability could be increased by the reduction of oxygen radicals or the removal of damaged molecules-DNA, protein. lipid membrane. or the removal of damaged cells. In this paper. we studied the radioresistance mechanism in lymphocytes and lymphoma cells by examining the activities of radical scavengers(catalase. peroxidase, superoxide dismutase, and glucose-6-phosphate dehydrogenase), and a radical protector(glutathione). Different enzymes were induced in lymphocyte and lymphoma with low-dose irradiation. The activity of peroxidase increased most(133.3%) in lymphoma while the enzymes increased most in lymphocyte were superoxide dismutase (138.5%), glucose-6-phosphate dehydrogenase (122.4%) and glutathione(120.8%). The activities of these enzymes were highest when the interval was 7 hours between low-dose and high-dose irradiation.

An electrolytic enrichment technique was used to measure low levels of tritium in seawater around the Korean peninsula. Tritium concentrations were determined for surface seawater samples collected from the East Sea, the South Sea, and the Yellow Sea. The tritium concentrations in surface seawater samples from the study area ranged from with a mean value of . The means of the tritium concentration were for the East Sea, for the South Sea, and for the Yellow Sea. The tritium concentrations in the sea areas did not show much difference no matter where the samples were taken. Due to the limited number and distribution of sampling points, no systematic change in tritium levels with latitude was observed. Measured tritium levels were similar to those observed in other data collected near Japan, but higher than mid-Pacific Ocean measurements.

Source intensities in terms of the exposure rates at 1m from the fresh and spent DUPIC fuels, made from standard and extended turnup PWR fuels, were analyzed. Two cases were studied based on the degree of elimination of removable elements. Homogeneous mixture model was applied to get the exposure rate. The exposure rate turned out to be very high and sensitive to Cs elimination during the dry process. About 90% of exposure can be reduced in the case of fresh DUPIC fuel made from 10-year cooled spent PWR fuels if Cs is fully removed during the dry process. The main radiation source in spent fuels is Cs-137. The dry storage of spent DUPIC fuel may need a longer wet storage period and require a further review.

The energy response of HPGe detector for low energy Photons was determined by using three Monte Carlo codes. MCNP4A. EGS4, and CYLTRAN in ITS3. In this study. bare HPGe detector was used and a pencil beam was incident perpendicularly on the center of the detector surface. The photopeak efficiency, and escape fractions were calculated as a function of incident X-ray energies ranging from 12 to 60 keV in 2-keV increments. Since the Compton. elastic. ana penetration fraction were negligible in this energy range. they were ignored in the calculation. Although MCNP. EGS, and CYLTRAN codes calculated slightly different energy response of HPGe detector for low energy Photons, it appears that the three Monte Carlo codes can Predict the low energy Photon scattering Processes accurately. The MCNP results, which are generally known as to be less accurate at low energy ranges than the EGS and ITS results. are comparable to the results of EGS and ITS and are applicable to the calculation of the low energy response data of a detector.

This paper describes the methods and results of the personnel dosimetry performance tests which were been implemented for the first time in Korea in 1995. Seven categories, except the neutron category prescribed in the ANSI N13.11-1993, were adopted in the test. Fifteen types of dosimeters were participated by fourteen dosimeter processing institutes. A total of 129 dosimeters were selected to test-each type - 15 dosimeters for each of the seven categories and 24 for the controls. A total of 144 radiation categories were employed in the test and a total of 2560 (including 400 controls)dosimeters were submitted-7 categories for each type of the fifteen types dosimeters and 39 categories for the retest. The performance index in each category. sum of the absolute value of the bias and the standard deviation value of the performance quotient. was estimated by the use of delivered and processed dose equivalents according to the standard procedure. The performance in a given category was assessed as acceptable, for the deep and shallow dose equivalents (or the absorbed dose), if the performance index was less than 0.5. The test results showed 54% of the processors passed in the first test, 33% in the retest and 13% in the second retest.

A multi-wire proportional counter with large sensitive area was designed and constructed considering diameter of anode wire. its material and space. A preamplifier connecting detector to main amplifier or counter was also designed and constructed for measurement output pulse from multi-wire proportional counter. The preamplifier was composed of charge-sensitive differential circuit. clipping circuit and amplification circuit. To test the performance of this equipment, terminal output pulse from the preamplifier was measured and compared with noise For these tests were used as radiation sources. The noise ingredient contributing to the maximum amplitude(180mV from and 200 mV from ) was found to be very small(8 mV) Piled up pulse occurring at the output pulse of charge-sensitive differential circuit was measured as an independent pulse since this affected the amplification in the clipping circuit and amplification circuit. This information can be used to improve the loss of measurement due to piled up pulse.